from math import sqrt
x_1,y_1,x_2,y_2=map(float,raw_input().split(" "))
print sqrt((x_1-x_2)**2 + (y_1-y_2)**2) from math import sqrt x_1,y_1,x_2,y_2=map(float,raw_input().split(" ")) x_1 map(float,raw_input().split(" ")) map float raw_input().split(" ") ().split () raw_input split " " y_1 x_2 y_2 print sqrt((x_1-x_2)**2 + (y_1-y_2)**2) sqrt (x_1-x_2)**2 + (y_1-y_2)**2 (x_1-x_2)**2 x_1-x_2 x_1 x_2 2 (y_1-y_2)**2 y_1-y_2 y_1 y_2 2 x_2,y_2=map(float,raw_input().split(" ")) map(float,raw_input().split(" ")) x_2 y_2=map(float,raw_input().split(" ")) map(float,raw_input().split(" ")) y_2 x_1,y_1,x_2,y_2=map(float,raw_input().split(" ")) map(float,raw_input().split(" ")) x_1 y_1,x_2,y_2=map(float,raw_input().split(" ")) map(float,raw_input().split(" ")) y_1
from math import sqrt
x_1,y_1,x_2,y_2=map(float,raw_input().split(" "))
print sqrt((x_1-x_2)**2 + (y_1-y_2)**2)